When machined or cast articles, such as dies, molds and the like, are initially manufactured, it is common for them to have moderate to poor surface finishes. In many instances, it is essential that these articles be prepared with a superior surface finish not having any surface defects. Any such surface defects would otherwise adversely affect the molded or casted product. These defects must be polished out or removed with a high degree of precision and without improperly changing the overall surface contour. For instance, it may require finishing the surface containers of the work piece to within one or two thousandths of an inch, or less, of the established specifications for the work piece. In other applications, mold making errors or structural defects must be corrected to ensure the work piece complies to exacting tolerances and clearances.
An abrasive tool is typically used to remove such defects or make such changes to a work piece. These abrasive tools can be made of a variety of materials, and include abrasive "stones." Such "stones" typically are compressed abrasive materials with a controlled surface texture with a certain abrasive grade based on the size of abrasive particles at the tool surface. These stones frequently must be handled with care to prevent breakage or cracking of the stone surface on the stone itself. In addition, the abrasive tool must be applied to the work piece surface with particular care because any imprecise or unpredictable tool motion can ruin the work piece mold or require additional cost to repair the damaged surface.
Power hand tools, generally referred to as profilers, are commonly used to assist in polishing and removing such surface defects and making surface changes. These profilers provide reciprocating movement to operate a suitable abrasive tool attachment. The reciprocating tool attachment is then directed at the surface areas of the article to remove unwanted surface material. As mentioned above, a profiler must effectively support the tool attachment to prevent it from wobbling; otherwise, the tool attachment may break or gouge the surface of the article.
In many profilers, the reciprocating movement for the tool attachment is derived from a drive rod following an off-centered rotating tuner mechanism. The drive rod then drives a linear drive mechanism having a tool holder for the tool attachment. The tuner mechanism is driven by an external source, such as a remote hydraulic or electric powered unit, preferably being equipped with a speed control unit which allows the profiler's speed to be adjusted according to the finishing process used and the tool attachment's requirements. Though capabilities vary from one profiler design to another, these tuner mechanisms are known to rotate at speeds in excess of 22,000 rpms or more, while speeds up to 5,000 rpms are most common. As a result, the drive rod is capable of driving the linear drive mechanism at significant speeds. Therefore, the linear drive mechanism must effectively support and guide the tool holder in a manner which is resistant to unnecessary component wear caused by significant speed operation so that the tool attachment reciprocates linearly in a single plane and, hence, is not allowed to wobble.
It is common for the linear drive mechanism to have components with engaging surfaces sliding over one another to precisely guide the linear reciprocating movement of the tool holder. These surfaces prevent the tool attachment from wobbling outside of the desired path of reciprocating movement. However, during operation, machining loads act on the tool holder from directions outside the desired path of reciprocating movement. Experience has revealed that these loads cause the engaging surfaces of the components to wear and rapidly lose proper engagement. As a result, the tool holder tends to wobble outside the desired path of reciprocating movement, which causes a decrease in the accuracy and precision that can be obtained with the abrasive tool. Any such decrease in accuracy may result in polishing or removal errors. Additionally, errors resulting from operator fatigue will increase because polishing and removal operations will take longer when attempting to compensate for the wobbling of the tool attachment.
Further, restoring the accuracy of the profiler becomes expensive as the life of profiler components decreases. To restore the profiler's accuracy, the components having the engaging surfaces must be replaced to reestablish the proper surface engagement necessary for precisely guiding the reciprocating movement of the tool holder. Often such replacement parts are not available and the entire profiler must be replaced. In addition to the cost of replacement pans and new profilers, the downtime associated with replacing pans and profilers also contributes significantly to the overall cost of machining operations.
Therefore, there is a desire for a profiler device that provides enhanced support for the tool holder to effectively accommodate machining loads outside the path of reciprocating movement for sustaining the accuracy and precision of the profiles and for reducing the expense associated with unnecessary downtime and replacement pans.
One known example for guiding a profiler's tool holder includes a tool support housing having a slot formed in its remote end that is in sliding engagement with a pair of opposed flats extending from a tool holder. This sliding engagement guides the reciprocating movement of the tool holder. Further, the tool holder is driven by a sleeve having a sliding surface engagement with a support housing which also aids in guiding the reciprocating movement of the tool holder.
One known shortcoming with this device is its inability to adequately support the tool holder for effectively accommodating machining loads outside the path of reciprocating movement. During machining operations, these machining loads cause the flats of the tool holder to wear the edges of the slots so that they become enlarged. This allows the tool holder and the tool to wobble. Also, other components, such as the reciprocating sleeve and the support housing, are found to wear more rapidly when the tool holder wobbles. These adverse effects contribute significantly to requiring the profiler components, including the tool, to be replaced more often than desired for maintaining machining accuracy.
An object of the present invention is to provide an improved guide system for the tool holder that advantageously extends the life of the tool and profiler components for maintaining accuracy and reducing machining costs.
Another object of the present invention is to provide a guide system in which the surface engagement used to guide the tool holder is increased to yield improved support against machining loads.
An even further object of the present invention is to provide a guide system that is more resistant to wear caused by machining loads.
An overall object of the present invention is to provide an improved guide system having all the above-mentioned objects which is highly durable, efficient and cost effective to manufacture, install and operate.
Other objects of the invention are discussed below and are shown in the figures.